1. Field
The disclosure relates to a hybrid vehicle in which an on-board electrical storage device can be charged by a power supply on the outside of the vehicle.
2. Description of Related Art
Japanese Patent Application Publication No. 2011-915 (JP 2011-915 A) discloses a hybrid vehicle that includes: an engine that generates power by using fuel; a battery that can be charged externally; and a motor generator that generates power by using electric power supplied from said battery. This hybrid vehicle is configured to control a drive ratio between the engine and the motor generator with respect to requested drive power such that the drive ratio of either the engine or the motor generator that can produce a higher economic effect is increased in accordance with unit distance fuel cost that is a unit price of the fuel reserved in the vehicle after refueling per unit distance and unit distance electric power cost that is a unit price of the electric power stored in the battery after electrical charging of the battery by external charging per unit distance.
In JP 2011-915 A, in the above configuration, an EV travel region in which the vehicle travels only by drive power of the motor generator is increased or decreased in accordance with a result of comparison of a magnitude between the unit distance fuel cost and the unit distance electric power cost. Alternatively, in accordance with the above comparison result, a cooperative travel region of the engine and the motor generator is increased or decreased, and the drive ratio between the engine and the motor generator in the cooperative travel region is changed.
In the hybrid vehicle as described above, engine output is appropriately controlled in order to control a state of charge (hereinafter also abbreviated as an SOC) of the battery to be an SOC target value. Energy efficiency (hereinafter also referred to as “charging efficiency”) of the increased SOC with respect to fuel consumption at this time is changed in accordance with an engine operation point that is defined by a combination of an engine speed and engine torque.
For example, in the case where an operation point at which power required for traveling of the vehicle is output is located on a low output side from an operation point at which engine efficiency becomes the maximum, the engine efficiency is improved by adding power for charging of the battery during charging by SOC control. In such a case, there is a possibility that charging cost of the battery by the engine output is lower than charging cost thereof by external charging.
Accordingly, it is considered that a total travel cost of the hybrid vehicle is rather increased in the case where the engine efficiency during the charging by the SOC control as described above is not taken into consideration and the external charging is uniformly performed.